The Claimants applied to revoke AstraZeneca’s patent EP (UK) 0 907 364 which was for a sustained release formulation of an anti-psychotic drug known as quetiapine (marketed as SEROQUEL).

The Claimants argued that the patent was invalid for obviousness in view of an item of prior art referred to as Gefvert. If claim 1 was invalid, AstraZeneca asserted that the only other independently valid claim was claim 15.

It was common ground that the only difference between Gefvert and claim 1 was that Gefvert did not disclose a sustained release formulation of any kind. Mr Justice Arnold held that the skilled team would consider that a sustained release formulation was likely to be efficacious and would be an obvious possibility to try and that the skilled team would not be deterred from developing a sustained release formulation because of quetiapine’s high first pass metabolism. As a result, claim 1 was invalid. Mr Justice Arnold also rejected the validity of claim 15 as it was directed towards the use of sodium citrate as a pH modifier for any purpose and not limited to its use to decrease solubility.